4 圖示電路中場效電晶體(FET)之 VTH = -0.7 V,下列電壓何者可使電晶體工作在飽和區(SaturationRegion)?(A) VG = 5 V、VD = 4 V(B) VG = 4 V、VD = 4 V(C) VG = 3 V、VD = 4 V(D) VG = 2 V、VD = 4 V